Spring shape updated to better support enabling/disabling and state o…

…bservation. Summary: Spring now has both a state and enabled property. The Spring instance's value stream is multicast, and the underlying system that drives this value stream is expected to update the spring's state property. This is a precursor to being able to delete the state channel in its entirety. I'll be cleaning up the mechanism by which the spring's value stream is created in a follow-up change. In order to keep the examples functioning, this change also introduces "terminal conditions" for transitions. This is a hack solution and will need to be iterated on. Reviewers: O4 Material Apple platform reviewers, appsforartists, #material_motion, O2 Material Motion Reviewed By: appsforartists, #material_motion, O2 Material Motion Subscribers: appsforartists Tags: #material_motion Differential Revision: http://codereview.cc/D2683
material-motion · Feb 16, 2017 · 41fee56 · 41fee56
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Showing 15 changed files with 229 additions and 148 deletions.
diff --git a/examples/ContextualTransitionExample.swift b/examples/ContextualTransitionExample.swift
@@ -275,14 +275,18 @@ private class PushBackTransitionDirector: TransitionDirector {
     let movement = spring(back: contextView, fore: foreImageView, transition: transition)
     let size = spring(back: contextView.bounds.size, fore: fitSize, threshold: 1, transition: transition)
 
+    var terminalStates = [movement.state.asStream(), size.state.asStream()]
+
     let pans = transition.gestureRecognizers.filter { $0 is UIPanGestureRecognizer }.map { $0 as! UIPanGestureRecognizer }
     for pan in pans {
       let atRestStream = runtime.get(pan).atRest()
-      movement.compose { $0.valve(openWhenTrue: atRestStream) }
-      size.compose { $0.valve(openWhenTrue: atRestStream) }
+      terminalStates.append(runtime.get(pan).asMotionState())
 
       let velocityStream = runtime.get(pan).velocityOnReleaseStream()
-      movement.add(initialVelocityStream: velocityStream)
+      runtime.add(velocityStream, to: movement.initialVelocity)
+
+      runtime.add(atRestStream, to: movement.enabled)
+      runtime.add(atRestStream, to: size.enabled)
 
       runtime.add(runtime.get(pan)
         .translation(in: runtime.containerView)
@@ -298,11 +302,15 @@ private class PushBackTransitionDirector: TransitionDirector {
 
     runtime.add(Hidden(), to: foreImageView)
 
-    runtime.add(spring(back: 0, fore: 1, threshold: 0.01, transition: transition),
-                to: runtime.get(transition.fore.view.layer).opacity)
+    let opacity: TransitionSpring<CGFloat> = spring(back: 0, fore: 1, threshold: 0.01, transition: transition)
+    runtime.add(opacity, to: runtime.get(transition.fore.view.layer).opacity)
+
+    terminalStates.append(opacity.state.asStream())
+
+    transition.terminateWhenAllAtRest(terminalStates)
   }
 
-  private func spring<T where T: Subtractable, T: Zeroable>(back: T, fore: T, threshold: CGFloat, transition: Transition) -> TransitionSpring<T> {
+  private func spring<T where T: Subtractable, T: Zeroable, T: Equatable>(back: T, fore: T, threshold: CGFloat, transition: Transition) -> TransitionSpring<T> {
     let spring = TransitionSpring(back: back, fore: fore, direction: transition.direction, threshold: threshold, system: coreAnimation)
     spring.friction.value = 500
     spring.tension.value = 1000

diff --git a/examples/DragSourceExample.swift b/examples/DragSourceExample.swift
@@ -97,6 +97,9 @@ public class DragSourceExampleViewController: UIViewController {
     let tossable = Tossable(destination: Destination(runtime.get(circle)), system: pop)
     runtime.add(tossable, to: square)
     runtime.add(Tap(), to: tossable)
-    runtime.add(Spring(to: tossable.destination.asProperty(), threshold: 1, system: coreAnimation), to: square2)
+
+    let spring = Spring<CGPoint>(threshold: 1, system: coreAnimation)
+    runtime.add(tossable.destination.asStream(), to: spring.destination)
+    runtime.add(spring, to: square2)
   }
 }
diff --git a/examples/InteractivePushBackTransitionExample.swift b/examples/InteractivePushBackTransitionExample.swift
@@ -77,17 +77,18 @@ private class PushBackTransitionDirector: TransitionDirector {
       switch gestureRecognizer {
       case let pan as UIPanGestureRecognizer:
         let gesture = runtime.get(pan)
+
         let dragStream = gesture.translated(from: foreLayer.position).y().min(foreLayer.layer.bounds.height / 2)
-        movement.compose { $0.toggled(with: dragStream) }
+        runtime.add(dragStream, to: foreLayer.positionY)
 
         let scaleStream = dragStream.mapRange(rangeStart:movement.backwardDestination,
                                               rangeEnd:movement.forwardDestination,
                                               destinationStart:scale.backwardDestination,
                                               destinationEnd:scale.forwardDestination)
-        scale.compose { $0.toggled(with: scaleStream) }
+        runtime.add(scaleStream, to: runtime.get(transition.back.view.layer).scale)
 
         let velocityStream = gesture.velocityOnReleaseStream().y()
-        movement.add(initialVelocityStream: velocityStream)
+        runtime.add(velocityStream, to: movement.initialVelocity)
 
         // TODO: Allow "whenWithin" to be a stream so that we can add additional logic for "have we
         // passed the y threshold?"
@@ -96,13 +97,19 @@ private class PushBackTransitionDirector: TransitionDirector {
                                              whenWithin: transition.direction.value,
                                              whenAbove: .backward),
                     to: transition.direction)
+
+        runtime.add(gesture.atRest(), to: movement.enabled)
+        runtime.add(gesture.atRest(), to: scale.enabled)
+
       default:
         ()
       }
     }
 
     runtime.add(movement, to: foreLayer.positionY)
     runtime.add(scale, to: runtime.get(transition.back.view.layer).scale)
+
+    transition.terminateWhenAllAtRest([movement.state.asStream(), scale.state.asStream()])
   }
 
   private func spring(back: CGFloat, fore: CGFloat, threshold: CGFloat, transition: Transition) -> TransitionSpring<CGFloat> {

diff --git a/examples/ModalDialogExample.swift b/examples/ModalDialogExample.swift
@@ -81,30 +81,33 @@ class ModalDialogTransitionDirector: SelfDismissingTransitionDirector {
     let backPositionY = bounds.maxY + size.height * 3 / 4
     let forePositionY = bounds.midY
 
-    let spring = TransitionSpring(back: backPositionY,
-                                  fore: forePositionY,
-                                  direction: transition.direction,
-                                  threshold: 1,
-                                  system: pop)
     let mainThreadReactive: Bool
+    let system: SpringToStream<CGFloat>
     if #available(iOS 9.0, *) {
       mainThreadReactive = false
-      spring.system = coreAnimation
+      system = coreAnimation
     } else {
       mainThreadReactive = true
+      system = pop
     }
+    let spring = TransitionSpring(back: backPositionY,
+                                  fore: forePositionY,
+                                  direction: transition.direction,
+                                  threshold: 1,
+                                  system: system)
 
     let reactiveForeLayer = runtime.get(transition.fore.view.layer)
 
     for gestureRecognizer in transition.gestureRecognizers {
       switch gestureRecognizer {
       case let pan as UIPanGestureRecognizer:
         let gesture = runtime.get(pan)
+
         let dragStream = gesture.translated(from: reactiveForeLayer.position).y()
-        spring.compose { $0.toggled(with: dragStream) }
+        runtime.add(dragStream, to: reactiveForeLayer.positionY)
 
         let velocityStream = gesture.velocityOnReleaseStream().y()
-        spring.add(initialVelocityStream: velocityStream)
+        runtime.add(velocityStream, to: spring.initialVelocity)
 
         let centerY = reactiveForeLayer.layer.bounds.height / 2.0
         let withinStream = reactiveForeLayer.positionY.threshold(centerY,
@@ -116,6 +119,9 @@ class ModalDialogTransitionDirector: SelfDismissingTransitionDirector {
                                              whenWithin: withinStream,
                                              whenAbove: .backward),
                     to: transition.direction)
+
+        runtime.add(gesture.atRest(), to: spring.enabled)
+
       default:
         ()
       }
@@ -131,6 +137,8 @@ class ModalDialogTransitionDirector: SelfDismissingTransitionDirector {
                   destinationEnd: 0)
       runtime.add(rotation, to: reactiveForeLayer.rotation)
     }
+
+    transition.terminateWhenAllAtRest([spring.state.asStream()])
   }
 
   static func willPresent(fore: UIViewController, dismisser: ViewControllerDismisser) {

diff --git a/examples/PushBackTransitionExample.swift b/examples/PushBackTransitionExample.swift
@@ -66,14 +66,16 @@ private class PushBackTransitionDirector: TransitionDirector {
   required init() {}
 
   func willBeginTransition(_ transition: Transition, runtime: MotionRuntime) {
-    runtime.add(spring(back: transition.containerView().bounds.height + transition.fore.view.layer.bounds.height / 2,
-                       fore: transition.containerView().bounds.midY,
-                       threshold: 1,
-                       transition: transition),
-                to: runtime.get(transition.fore.view.layer).positionY)
-
-    runtime.add(spring(back: 1, fore: 0.95, threshold: 0.005, transition: transition),
-                to: runtime.get(transition.back.view.layer).scale)
+    let position = spring(back: transition.containerView().bounds.height + transition.fore.view.layer.bounds.height / 2,
+                          fore: transition.containerView().bounds.midY,
+                          threshold: 1,
+                          transition: transition)
+    let scale = spring(back: 1, fore: 0.95, threshold: 0.005, transition: transition)
+
+    runtime.add(position, to: runtime.get(transition.fore.view.layer).positionY)
+    runtime.add(scale, to: runtime.get(transition.back.view.layer).scale)
+
+    transition.terminateWhenAllAtRest([position.state.asStream(), scale.state.asStream()])
   }
 
   private func spring(back: CGFloat, fore: CGFloat, threshold: CGFloat, transition: Transition) -> TransitionSpring<CGFloat> {

diff --git a/examples/StickerPickerExample.swift b/examples/StickerPickerExample.swift
@@ -53,7 +53,8 @@ public class StickerPickerExampleViewController: UIViewController, StickerListVi
     view.addSubview(imageView)
 
     imageView.layer.transform = CATransform3DMakeScale(1.5, 1.5, 1)
-    let spring = Spring(to: CGFloat(1), threshold: 1, system: coreAnimation)
+    let spring = Spring<CGFloat>(threshold: 1, system: coreAnimation)
+    spring.destination.value = 1
     runtime.add(spring, to: runtime.get(imageView.layer).scale)
 
     runtime.add(DirectlyManipulable(targetView: imageView), to: imageView)
@@ -206,5 +207,7 @@ private class ModalTransitionDirector: TransitionDirector {
                                   threshold: 0.01,
                                   system: coreAnimation)
     runtime.add(spring, to: runtime.get(transition.fore.view.layer).opacity)
+
+    transition.terminateWhenAllAtRest([spring.state.asStream()])
   }
 }
diff --git a/examples/SwipeExample.swift b/examples/SwipeExample.swift
@@ -73,14 +73,15 @@ class TossableStackedCard: ViewInteraction {
     runtime.add(gestureEnabledStream, to: drag.isEnabled)
     runtime.add(gestureEnabledStream, to: reactiveView.isUserInteractionEnabled)
 
-    let attachment = Spring(to: destination,
-                            initialVelocity: drag.velocityOnReleaseStream(in: view).x(),
-                            threshold: 1,
-                            system: pop)
+    let attachment = Spring<CGFloat>(threshold: 1, system: pop)
+    runtime.add(drag.velocityOnReleaseStream(in: view).x(), to: attachment.initialVelocity)
+    runtime.add(destination.asStream(), to: attachment.destination)
+    runtime.add(reactiveView.centerX.asStream(), to: attachment.initialValue)
 
     let draggable = drag.translated(from: reactiveView.center, in: relativeView).x()
-    runtime.add(attachment.stream(withInitialValue: reactiveView.centerX).toggled(with: draggable),
-                           to: reactiveView.centerX)
+    runtime.add(draggable, to: reactiveView.centerX)
+    runtime.add(drag.atRest(), to: attachment.enabled)
+    runtime.add(attachment, to: reactiveView.centerX)
 
     let radians = CGFloat(M_PI / 180.0 * 15.0)
     let rotationStream =
@@ -101,7 +102,8 @@ class TossableStackedCard: ViewInteraction {
           .max(1)
           .subtracted(from: 1)
           .scaled(by: rotation)
-      runtime.add(nextRotationStream.toggled(with: rotationStream), to: reactiveLayer.rotation)
+      runtime.add(nextRotationStream.valve(openWhenTrue: drag.atRest()), to: reactiveLayer.rotation)
+      runtime.add(rotationStream.valve(openWhenTrue: drag.active()), to: reactiveLayer.rotation)
     } else {
       runtime.add(rotationStream, to: reactiveLayer.rotation)
     }

diff --git a/src/interactions/Spring.swift b/src/interactions/Spring.swift
@@ -15,38 +15,30 @@
  */
 
 import Foundation
-import IndefiniteObservable
 
 /**
  A Spring can pull a value from an initial position to a destination using a physical simulation.
 
  This class defines the expected shape of a Spring for use in creating a Spring source.
  */
-public class Spring<T: Zeroable>: ViewInteraction, PropertyInteraction {
-
-  /** Creates a spring with the provided properties and an initial velocity of zero. */
-  public convenience init<O: MotionObservableConvertible>(to destination: O, threshold: CGFloat, system: @escaping SpringToStream<T>) where O.T == T {
-    let initialVelocity = createProperty(withInitialValue: T.zero() as! T)
-    self.init(to: destination, initialVelocity: initialVelocity, threshold: threshold, system: system)
-  }
-
+public class Spring<T: Zeroable>: PropertyInteraction, ViewInteraction {
   /** Creates a spring with the provided properties and an initial velocity. */
-  public init<O1: MotionObservableConvertible, O2: MotionObservableConvertible>(to destination: O1,
-              initialVelocity: O2,
-              threshold: CGFloat,
-              system: @escaping SpringToStream<T>) where O1.T == T, O2.T == T {
-    self.destination = destination.asStream()
-    self.initialVelocity = initialVelocity.asStream()
-    self.system = system
-
+  public init(threshold: CGFloat, system: @escaping SpringToStream<T>) {
     self.threshold = createProperty(withInitialValue: threshold)
+    self.system = system
   }
 
-  /** The destination value of the spring represented as a property. */
-  public let destination: MotionObservable<T>
+  public let enabled = createProperty(withInitialValue: true)
+
+  public let state = createProperty(withInitialValue: MotionState.atRest)
+
+  public let initialValue: ReactiveProperty<T> = createProperty()
 
   /** The initial velocity of the spring represented as a stream. */
-  public private(set) var initialVelocity: MotionObservable<T>
+  public let initialVelocity: ReactiveProperty<T> = createProperty()
+
+  /** The destination value of the spring represented as a property. */
+  public let destination: ReactiveProperty<T> = createProperty()
 
   /** The tension configuration of the spring represented as a property. */
   public let tension = createProperty(withInitialValue: defaultSpringTension)
@@ -69,31 +61,29 @@ public class Spring<T: Zeroable>: ViewInteraction, PropertyInteraction {
   /** The value used when determining completion of the spring simulation. */
   public let threshold: ReactiveProperty<CGFloat>
 
-  public var system: SpringToStream<T>
-
-  /** The stream of values generated by this spring. */
-  public func stream<O: MotionObservableConvertible>(withInitialValue initialValue: O) -> MotionObservable<T> where O.T == T {
-    return compositions.reduce(system(self, initialValue.asStream())) { $1($0) }
-  }
-
-  public func compose(stream: @escaping (MotionObservable<T>) -> MotionObservable<T>) {
-    compositions.append(stream)
-  }
-  private var compositions: [(MotionObservable<T>) -> MotionObservable<T>] = []
+  fileprivate var stream: MotionObservable<T>?
+  fileprivate let system: SpringToStream<T>
 
   public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
     if let castedSelf = self as? Spring<CGPoint> {
       let position = reactiveView.reactiveLayer.position
-      runtime.add(castedSelf.stream(withInitialValue: position), to: position)
+      runtime.add(position.asStream(), to: castedSelf.initialValue)
+      runtime.add(castedSelf.asStream(), to: position)
     }
   }
 
   public func add(to property: ReactiveProperty<T>, withRuntime runtime: MotionRuntime) {
-    runtime.add(stream(withInitialValue: property), to: property)
+    runtime.add(property.asStream(), to: initialValue)
+    runtime.add(asStream(), to: property)
   }
+}
 
-  public func add(initialVelocityStream stream: MotionObservable<T>) {
-    initialVelocity = initialVelocity.merge(with: stream)
+extension Spring: MotionObservableConvertible {
+  public func asStream() -> MotionObservable<T> {
+    if stream == nil {
+      stream = system(self).multicast()
+    }
+    return stream!
   }
 }
 

diff --git a/src/interactions/Tossable.swift b/src/interactions/Tossable.swift
@@ -46,15 +46,17 @@ public class Tossable: ViewInteraction {
   public func add(to reactiveView: ReactiveUIView, withRuntime runtime: MotionRuntime) {
     let position = reactiveView.reactiveLayer.position
     let relativeView = draggable.relativeView ?? runtime.containerView
-
     let gesture = runtime.get(draggable.gestureRecognizer)
-    let spring = Spring(to: destination,
-                        initialVelocity: gesture.velocityOnReleaseStream(in: relativeView),
-                        threshold: 1,
-                        system: system)
-    let dragStream = gesture.translated(from: reactiveView.center, in: relativeView)
-    let tossStream = spring.stream(withInitialValue: reactiveView.center).toggled(with: dragStream)
-    runtime.add(tossStream, to: reactiveView.center)
+
+    runtime.add(gesture.translated(from: position, in: relativeView), to: position)
+
+    let spring = Spring(threshold: 1, system: system)
+    runtime.add(destination.asStream(), to: spring.destination)
+    runtime.add(position.asStream(), to: spring.initialValue)
+    runtime.add(gesture.velocityOnReleaseStream(in: relativeView), to: spring.initialVelocity)
+    runtime.add(spring, to: position)
+
+    runtime.add(gesture.atRest(), to: spring.enabled)
   }
 }
 

diff --git a/src/interactions/TransitionSpring.swift b/src/interactions/TransitionSpring.swift
@@ -41,19 +41,20 @@ public class TransitionSpring<T: Zeroable>: Spring<T>, TransitionInteraction {
     self.forwardDestination = forwardDestination
     self._initialValue = direction == .forward ? backwardDestination : forwardDestination
 
-    let destinationStream = direction.stream.destinations(back: backwardDestination,
-                                                         fore: forwardDestination)
-    let initialVelocity = createProperty(withInitialValue: T.zero() as! T)
-    super.init(to: destinationStream, initialVelocity: initialVelocity, threshold: threshold, system: system)
+    self.toggledDestination = direction.stream.destinations(back: backwardDestination,
+                                                            fore: forwardDestination)
+    super.init(threshold: threshold, system: system)
   }
 
   public override func add(to property: ReactiveProperty<T>, withRuntime runtime: MotionRuntime) {
-    runtime.add(stream(withInitialValue: property), to: property)
+    runtime.add(toggledDestination, to: destination)
+    super.add(to: property, withRuntime: runtime)
   }
 
   public func initialValue() -> T {
     return _initialValue
   }
 
   private let _initialValue: T
+  private let toggledDestination: MotionObservable<T>
 }
diff --git a/src/sources/SpringToStream.swift b/src/sources/SpringToStream.swift
@@ -19,4 +19,4 @@ import UIKit
 /**
  A spring-to-stream function creates a MotionObservable from a Spring and initial value stream.
  */
-public typealias SpringToStream<T: Zeroable> = (Spring<T>, MotionObservable<T>) -> MotionObservable<T>
+public typealias SpringToStream<T: Zeroable> = (Spring<T>) -> MotionObservable<T>